[PATCH v4 0/2] Add TI SCI Reset Driver

[PATCH v4 0/2] Add TI SCI Reset Driver

[Andrew F. Davis]

Hello all,

This series adds a reset controller driver that uses the TI SCI
protocol to manage resets.

The TI SCI protocol is used to communicate with power management
controllers used by some SoCs. These controllers manage the various
power domains, clocks, and resets available on a SoC.

This series is based on drivers for TI SCI and the first two controlled
elements above, these series can be found here:

TI-SCI: http://www.spinics.net/lists/arm-kernel/msg536851.html
PM Domains: http://www.spinics.net/lists/devicetree/msg146621.html
Clocks: https://www.spinics.net/lists/linux-clk/msg12785.html

Thanks,
Andrew

Changes from v3:
 - Addressed Rob Herring's comments
 - Added Santosh Shilimkar's Ack

Changes from v2:
 - Merged DT binding patch and reset header patch
 - Added locking for reset bit mask

Changes from v1:
 - Revised dt binding
 - CC Linux ARM list

Andrew F. Davis (2):
  Documentation: dt: reset: Add TI SCI reset binding
  reset: Add the TI SCI reset driver

 .../devicetree/bindings/reset/ti,sci-reset.txt     |  66 +++++
 MAINTAINERS                                        |   3 +
 drivers/reset/Kconfig                              |   9 +
 drivers/reset/Makefile                             |   1 +
 drivers/reset/reset-ti-sci.c                       | 272 +++++++++++++++++++++
 include/dt-bindings/reset/k2g.h                    |  22 ++
 6 files changed, 373 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/ti,sci-reset.txt
 create mode 100644 drivers/reset/reset-ti-sci.c
 create mode 100644 include/dt-bindings/reset/k2g.h

-- 
2.10.2

[PATCH v4 1/2] Documentation: dt: reset: Add TI SCI reset binding

[Andrew F. Davis]

Add TI SCI reset controller binding. This describes the DT binding
details for a reset controller node providing reset management services
to hardware blocks (reset consumers) using the Texas Instrument's System
Control Interface (TI SCI) protocol to communicate to a system controller
block present on the SoC.

Signed-off-by: Andrew F. Davis <afd@ti.com>
[s-anna@ti.com: revise the binding format]
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
---
 .../devicetree/bindings/reset/ti,sci-reset.txt     | 66 ++++++++++++++++++++++
 MAINTAINERS                                        |  2 +
 include/dt-bindings/reset/k2g.h                    | 22 ++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/ti,sci-reset.txt
 create mode 100644 include/dt-bindings/reset/k2g.h

diff --git a/Documentation/devicetree/bindings/reset/ti,sci-reset.txt b/Documentation/devicetree/bindings/reset/ti,sci-reset.txt
new file mode 100644
index 0000000..820c5d9
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/ti,sci-reset.txt
@@ -0,0 +1,66 @@
+Texas Instruments System Control Interface (TI-SCI) Reset Controller
+=====================================================================
+
+Some TI SoCs contain a system controller (like the Power Management Micro
+Controller (PMMC) on Keystone K2G SoC) that are responsible for controlling
+the state of the various hardware modules present on the SoC. Communication
+between the host processor running an OS and the system controller happens
+through a protocol called TI System Control Interface (TI-SCI protocol).
+For TI SCI details, please refer to the document,
+Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
+
+TI-SCI Reset Controller Node
+============================
+This reset controller node uses the TI SCI protocol to perform the reset
+management of various hardware modules present on the SoC. Must be a child
+node of the associated TI-SCI system controller node.
+
+Required properties:
+--------------------
+ - compatible	: Should be "ti,sci-reset"
+ - #reset-cells	: Should be 2. Please see the reset consumer node below for
+		  usage details.
+
+TI-SCI Reset Consumer Nodes
+===========================
+Each of the reset consumer nodes should have the following properties,
+in addition to their own properties.
+
+Required properties:
+--------------------
+ - resets	: A phandle and reset specifier pair, one pair for each reset
+		  signal that affects the device, or that the device manages.
+		  The phandle should point to the TI-SCI reset controller node,
+		  and the reset specifier should have 2 cell-values. The first
+		  cell should contain the device ID, the values of which are
+		  specified in the <dt-bindings/genpd/<soc>.h> include file.
+		  The second cell should contain the reset mask value used by
+		  system controller, the values of which are specified in the
+		  include file <dt-bindings/reset/<soc>.h>, where <soc> is the
+		  name of the SoC involved, for example 'k2g'.
+
+Please also refer to Documentation/devicetree/bindings/reset/reset.txt for
+common reset controller usage by consumers.
+
+Example:
+--------
+The following example demonstrates both a TI-SCI reset controller node and a
+consumer (a DSP device) on the K2G SoC.
+
+#include <dt-bindings/genpd/k2g.h>
+#include <dt-bindings/reset/k2g.h>
+
+pmmc: pmmc {
+	compatible = "ti,k2g-sci";
+
+	k2g_reset: reset-controller {
+		compatible = "ti,sci-reset";
+		#reset-cells = <2>;
+	};
+};
+
+dsp0: dsp0 {
+	...
+	resets = <&k2g_reset K2G_DEV_CGEM0 K2G_DEV_CGEM0_DSP0_RESET>;
+	...
+};
diff --git a/MAINTAINERS b/MAINTAINERS
index 6e93976..accf991 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11899,6 +11899,8 @@ F:	drivers/soc/ti/ti_sci_pm_domains.c
 F:	Documentation/devicetree/bindings/clock/ti,sci-clk.txt
 F:	include/dt-bindings/clock/k2g.h
 F:	drivers/clk/keystone/sci-clk.c
+F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
+F:	include/dt-bindings/reset/k2g.h
 
 THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
 M:	Hans Verkuil <hverkuil@xs4all.nl>
diff --git a/include/dt-bindings/reset/k2g.h b/include/dt-bindings/reset/k2g.h
new file mode 100644
index 0000000..00e2a9b
--- /dev/null
+++ b/include/dt-bindings/reset/k2g.h
@@ -0,0 +1,22 @@
+/*
+ * TI K2G SoC reset definitions
+ *
+ * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __DT_BINDINGS_RESET_K2G_H__
+#define __DT_BINDINGS_RESET_K2G_H__
+
+#define K2G_DEV_CGEM0_DSP0_RESET	0x1
+
+#endif
-- 
2.10.2

[PATCH v4 2/2] reset: Add the TI SCI reset driver

[Andrew F. Davis]

Some TI Keystone family of SoCs contain a system controller (like the
Power Management Micro Controller (PMMC) on K2G SoCs) that manage the
low-level device control (like clocks, resets etc) for the various
hardware modules present on the SoC. These device control operations
are provided to the host processor OS through a communication protocol
called the TI System Control Interface (TI SCI) protocol.

This patch adds a reset driver that communicates to the system
controller over the TI SCI protocol for performing reset management
of various devices present on the SoC. Various reset functionalities
are achieved by the means of different TI SCI device operations
provided by the TI SCI framework.

Signed-off-by: Andrew F. Davis <afd@ti.com>
[s-anna@ti.com: documentation changes, revised commit message]
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
---
 MAINTAINERS                  |   1 +
 drivers/reset/Kconfig        |   9 ++
 drivers/reset/Makefile       |   1 +
 drivers/reset/reset-ti-sci.c | 272 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 283 insertions(+)
 create mode 100644 drivers/reset/reset-ti-sci.c

diff --git a/MAINTAINERS b/MAINTAINERS
index accf991..b93d91a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11901,6 +11901,7 @@ F:	include/dt-bindings/clock/k2g.h
 F:	drivers/clk/keystone/sci-clk.c
 F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
 F:	include/dt-bindings/reset/k2g.h
+F:	drivers/reset/reset-ti-sci.c
 
 THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
 M:	Hans Verkuil <hverkuil@xs4all.nl>
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 06d9fa2..4c21c9d 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -66,6 +66,15 @@ config RESET_SUNXI
 	help
 	  This enables the reset driver for Allwinner SoCs.
 
+config RESET_TI_SCI
+	tristate "TI System Control Interface (TI-SCI) reset driver"
+	depends on RESET_CONTROLLER
+	depends on TI_SCI_PROTOCOL
+	help
+	  This enables the reset driver support over TI System Control Interface
+	  available on some new TI's SoCs. If you wish to use reset resources
+	  managed by the TI System Controller, say Y here. Otherwise, say N.
+
 config TI_SYSCON_RESET
 	tristate "TI SYSCON Reset Driver"
 	depends on HAS_IOMEM
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index bbe7026..36321f2 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
 obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
 obj-$(CONFIG_RESET_STM32) += reset-stm32.o
 obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
+obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
 obj-$(CONFIG_TI_SYSCON_RESET) += reset-ti-syscon.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
diff --git a/drivers/reset/reset-ti-sci.c b/drivers/reset/reset-ti-sci.c
new file mode 100644
index 0000000..9ac8499
--- /dev/null
+++ b/drivers/reset/reset-ti-sci.c
@@ -0,0 +1,272 @@
+/*
+ * Texas Instrument's System Control Interface (TI-SCI) reset driver
+ *
+ * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/
+ *	Andrew F. Davis <afd@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/idr.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/soc/ti/ti_sci_protocol.h>
+
+/**
+ * struct ti_sci_reset_control - reset control structure
+ * @dev_id: SoC-specific device identifier
+ * @reset_mask: reset mask to use for toggling reset
+ * @lock: synchronize reset_mask read-modify-writes
+ */
+struct ti_sci_reset_control {
+	u32 dev_id;
+	u32 reset_mask;
+	struct mutex lock;
+};
+
+/**
+ * struct ti_sci_reset_data - reset controller information structure
+ * @rcdev: reset controller entity
+ * @dev: reset controller device pointer
+ * @sci: TI SCI handle used for communication with system controller
+ * @idr: idr structure for mapping ids to reset control structures
+ */
+struct ti_sci_reset_data {
+	struct reset_controller_dev rcdev;
+	struct device *dev;
+	const struct ti_sci_handle *sci;
+	struct idr idr;
+};
+
+#define to_ti_sci_reset_data(p)	\
+	container_of((p), struct ti_sci_reset_data, rcdev)
+
+/**
+ * ti_sci_reset_set() - program a device's reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to toggle
+ * @assert: boolean flag to indicate assert or deassert
+ *
+ * This is a common internal function used to assert or deassert a device's
+ * reset using the TI SCI protocol. The device's reset is asserted if the
+ * @assert argument is true, or deasserted if @assert argument is false.
+ * The mechanism itself is a read-modify-write procedure, the current device
+ * reset register is read using a TI SCI device operation, the new value is
+ * set or un-set using the reset's mask, and the new reset value written by
+ * using another TI SCI device operation.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_set(struct reset_controller_dev *rcdev,
+			    unsigned long id, bool assert)
+{
+	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
+	const struct ti_sci_handle *sci = data->sci;
+	const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
+	struct ti_sci_reset_control *control;
+	u32 reset_state;
+	int ret;
+
+	control = idr_find(&data->idr, id);
+	if (!control)
+		return -EINVAL;
+
+	mutex_lock(&control->lock);
+
+	ret = dev_ops->get_device_resets(sci, control->dev_id,
+					 &reset_state);
+	if (ret)
+		goto out;
+
+	if (assert)
+		reset_state |= control->reset_mask;
+	else
+		reset_state &= ~control->reset_mask;
+
+	ret = dev_ops->set_device_resets(sci, control->dev_id,
+				         reset_state);
+out:
+	mutex_unlock(&control->lock);
+
+	return ret;
+}
+
+/**
+ * ti_sci_reset_assert() - assert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be asserted
+ *
+ * This function implements the reset driver op to assert a device's reset
+ * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
+ * with the corresponding parameters as passed in, but with the @assert
+ * argument set to true for asserting the reset.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	return ti_sci_reset_set(rcdev, id, true);
+}
+
+/**
+ * ti_sci_reset_deassert() - deassert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be deasserted
+ *
+ * This function implements the reset driver op to deassert a device's reset
+ * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
+ * with the corresponding parameters as passed in, but with the @assert
+ * argument set to false for deasserting the reset.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,
+				 unsigned long id)
+{
+	return ti_sci_reset_set(rcdev, id, false);
+}
+
+/**
+ * ti_sci_reset_status() - check device reset status
+ * @rcdev: reset controller entity
+ * @id: ID of reset to be checked
+ *
+ * This function implements the reset driver op to return the status of a
+ * device's reset using the TI SCI protocol. The reset register value is read
+ * by invoking the TI SCI device operation .get_device_resets(), and the
+ * status of the specific reset is extracted and returned using this reset's
+ * reset mask.
+ *
+ * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
+ */
+static int ti_sci_reset_status(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
+	const struct ti_sci_handle *sci = data->sci;
+	const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
+	struct ti_sci_reset_control *control;
+	u32 reset_state;
+	int ret;
+
+	control = idr_find(&data->idr, id);
+	if (!control)
+		return -EINVAL;
+
+	ret = dev_ops->get_device_resets(sci, control->dev_id,
+					 &reset_state);
+	if (ret)
+		return ret;
+
+	return reset_state & control->reset_mask;
+}
+
+static struct reset_control_ops ti_sci_reset_ops = {
+	.assert		= ti_sci_reset_assert,
+	.deassert	= ti_sci_reset_deassert,
+	.status		= ti_sci_reset_status,
+};
+
+/**
+ * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID
+ * @rcdev: reset controller entity
+ * @reset_spec: OF reset argument specifier
+ *
+ * This function performs the translation of the reset argument specifier
+ * values defined in a reset consumer device node. The function allocates a
+ * reset control structure for that device reset, and will be used by the
+ * driver for performing any reset functions on that reset. An idr structure
+ * is allocated and used to map to the reset control structure. This idr
+ * is used by the driver to do reset lookups.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,
+				 const struct of_phandle_args *reset_spec)
+{
+	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
+	struct ti_sci_reset_control *control;
+
+	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
+		return -EINVAL;
+
+	control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);
+	if (!control)
+		return -ENOMEM;
+
+	control->dev_id = reset_spec->args[0];
+	control->reset_mask = reset_spec->args[1];
+	mutex_init(&control->lock);
+
+	return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);
+}
+
+static const struct of_device_id ti_sci_reset_of_match[] = {
+	{ .compatible = "ti,sci-reset", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);
+
+static int ti_sci_reset_probe(struct platform_device *pdev)
+{
+	struct ti_sci_reset_data *data;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->sci = devm_ti_sci_get_handle(&pdev->dev);
+	if (IS_ERR(data->sci))
+		return PTR_ERR(data->sci);
+
+	data->rcdev.ops = &ti_sci_reset_ops;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.of_node = pdev->dev.of_node;
+	data->rcdev.of_reset_n_cells = 2;
+	data->rcdev.of_xlate = ti_sci_reset_of_xlate;
+	data->dev = &pdev->dev;
+	idr_init(&data->idr);
+
+	platform_set_drvdata(pdev, data);
+
+	return reset_controller_register(&data->rcdev);
+}
+
+static int ti_sci_reset_remove(struct platform_device *pdev)
+{
+	struct ti_sci_reset_data *data = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&data->rcdev);
+
+	idr_destroy(&data->idr);
+
+	return 0;
+}
+
+static struct platform_driver ti_sci_reset_driver = {
+	.probe = ti_sci_reset_probe,
+	.remove = ti_sci_reset_remove,
+	.driver = {
+		.name = "ti-sci-reset",
+		.of_match_table = ti_sci_reset_of_match,
+	},
+};
+module_platform_driver(ti_sci_reset_driver);
+
+MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
+MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
+MODULE_LICENSE("GPL v2");
-- 
2.10.2

Re: [PATCH v4 1/2] Documentation: dt: reset: Add TI SCI reset binding

[Rob Herring]

On Mon, Nov 21, 2016 at 03:30:51PM -0600, Andrew F. Davis wrote:
> Add TI SCI reset controller binding. This describes the DT binding
> details for a reset controller node providing reset management services
> to hardware blocks (reset consumers) using the Texas Instrument's System
> Control Interface (TI SCI) protocol to communicate to a system controller
> block present on the SoC.
> 
> Signed-off-by: Andrew F. Davis <afd@ti.com>
> [s-anna@ti.com: revise the binding format]
> Signed-off-by: Suman Anna <s-anna@ti.com>
> Signed-off-by: Nishanth Menon <nm@ti.com>
> Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
> ---
>  .../devicetree/bindings/reset/ti,sci-reset.txt     | 66 ++++++++++++++++++++++
>  MAINTAINERS                                        |  2 +
>  include/dt-bindings/reset/k2g.h                    | 22 ++++++++
>  3 files changed, 90 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reset/ti,sci-reset.txt
>  create mode 100644 include/dt-bindings/reset/k2g.h

Acked-by: Rob Herring <robh@kernel.org>